1. Field of the Invention
The present invention relates to an amplifier capable of controlling cut-off frequency in real time and an amplification method for controlling cut-off frequency in real time, and more particularly, to an amplifier capable of controlling cut-off frequency in real time and an amplification method for controlling cut-off frequency in real time
2. Description of the Related Art
Characteristics of a loudspeaker are determined by its design. For instance, a woofer has a relatively large diameter suitable for reproducing an audio signal in a low frequency band while a tweeter has a relatively small diameter suitable for reproducing an audio signal in a high frequency band. The woofer has a large displacement when reproducing the audio signal in the low frequency band while the tweeter has a small displacement when reproducing the audio signal in the high frequency band. The displacement refers to a moving distance of a diaphragm or a cone of the loudspeaker. That is, the diaphragm or the cone swings back and forth by a long distance when the displacement is large, and the diaphragm or the cone swings back and forth by a short distance when the displacement is small.
In order to reproduce the audio signal without distortions, audio signal in an appropriate frequency band should be applied to the loudspeaker. For instance, the audio signal in the high frequency band should be applied to the tweeter in order to prevent distortions and damages. Thus, an audio playback device divides the audio signal according to the frequency band by proper filtering and applies the divided audio signal to corresponding loudspeakers.
Recently, the audio playback device is becoming smaller and thinner. Accordingly, the size and the thickness of a loudspeaker is also being reduced. For instance, latest digital televisions employ LCDs and digital audio amplifiers to drastically reduce the thickness thereof compared to conventional television. The size and the thickness of the loudspeakers in the digital televisions are also being reduced accordingly, resulting in loudspeakers having poor playback capability of audio signal in low frequency band.
Moreover, the enhancement in the playback capability of audio signal in low frequency band in a car stereo system is in trend. However, it is difficult to enhance the playback capability due to the structural characteristic of an automobile.
In order to solve above-described problems, equalizers are employed in the audio playback device capable of controlling a level of bass according to a user's input. However, a distortion or a rattling may occur when the user excessively enhances the bass.